ORCID Profile
0000-0002-5131-8209
Current Organisation
Universiteit Gent
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Publisher: The Royal Society
Date: 25-01-2012
Abstract: Relative to other metazoans, the mammalian integument is thought to be limited in colour. In particular, while iridescence is widespread among birds and arthropods, it has only rarely been reported in mammals. Here, we examine the colour, morphology and optical mechanisms in hairs from four species of golden mole (Mammalia: Chrysochloridae) that are characterized by sheens ranging from purple to green. Microspectrophotometry reveals that this colour is weak and variable. Iridescent hairs are flattened and have highly reduced cuticular scales, providing a broad and smooth surface for light reflection. These scales form multiple layers of light and dark materials of consistent thickness, strikingly similar to those in the elytra of iridescent beetles. Optical modelling suggests that the multi-layers produce colour through thin-film interference, and that the sensitivity of this mechanism to slight changes in layer thickness and number explains colour variability. While coloured integumentary structures are typically thought to evolve as sexual ornaments, the blindness of golden moles suggests that the colour may be an epiphenomenon resulting from evolution via other selective factors, including the ability to move and keep clean in dirt and sand.
Publisher: Wiley
Date: 29-01-2015
DOI: 10.1111/ETH.12359
Publisher: Oxford University Press (OUP)
Date: 10-2015
DOI: 10.1642/AUK-15-14.1
Publisher: The Company of Biologists
Date: 2020
DOI: 10.1242/JEB.228387
Abstract: The costs associated with the production and maintenance of colour patches is thought to maintain their honesty. Although considerable research on sexual selection has focused on structurally coloured plumage ornaments, the proximate mechanisms of their potential condition-dependence, and thus their honesty, is rarely addressed, particularly in an experimental context. Blue tit (Cyanistes caeruleus) nestlings have UV-blue structurally coloured tail feathers, providing a unique opportunity for investigation of the causes of variation in their colour. Here, we examined the influence of early growing conditions on reflectance and structural properties of UV-blue coloured tail feathers of blue tit nestlings. We applied a two-stage brood size manipulation to determine which stage of development more strongly impacts the quality of tail feather colouration and microstructure. We used small angle X-ray scattering (SAXS) and electron microscopy to characterize nano- and micro-scale structure of tail feather barbs. Nestlings from the broods enlarged at a later stage of growth showed a sex-specific rectrix development delay, with males being more sensitive to this manipulation. Contrary to predictions, treatment affected neither the quality of the barb's nanostructures nor the brightness and UV chroma of feathers. However, at the micro-scale, barb's keratin characteristics were impaired in late-enlarged broods. Our results suggest that nanostructure quality, which determines UV-blue colour in tail feathers, is not sensitive to early rearing conditions. Furthermore, availability of resources during feather growth seems to impact the quality of feather microstructure more than body condition, which is likely determined at an earlier stage of nestling growth.
Publisher: The Company of Biologists
Date: 2013
DOI: 10.1242/JEB.098343
Abstract: Infection is an important source of mortality for avian embryos but parental behaviors and eggs themselves can provide a network of antimicrobial defenses. Mound builders (Aves: Megapodiidae) are unique among birds in that they produce heat for developing embryos not by sitting on eggs but by burying them in carefully tended mounds of soil and microbially decomposing vegetation. The low infection rate of eggs of one species in particular, the Australian brush-turkey (Alectura lathami) suggests that they possess strong defensive mechanisms. To identify some of these mechanisms we first quantified antimicrobial albumen proteins and characterized eggshell structure, finding that albumen was not unusually antimicrobial, but that eggshell cuticle was composed of nanometer-sized calcite spheres. Experimental tests revealed that these modified eggshells were significantly more hydrophobic and better at preventing bacterial attachment and penetration into the egg contents than chicken eggs. Our results suggest that these mechanisms may contribute to the antimicrobial defense system of these eggs, and may provide inspiration for new biomimetic anti-fouling surfaces.
Location: United States of America
No related grants have been discovered for Matthew Shawkey.